US9382801B2 - Method for removing a rotor bucket from a turbomachine rotor wheel - Google Patents

Abstract

A method of removing a bucket from a turbomachine rotor wheel includes exposing a base portion of the bucket, positioning a pulling device radially outwardly of the base portion, connecting the base portion of the bucket to the pulling device through a linking rod, exerting an axially outwardly directed force on the linking rod through the pulling device, and removing the base portion from the rotor wheel.

Description

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to the art of turbomachines and, more particularly, to a method of removing a rotor bucket from a turbomachine rotor wheel.

Steam turbines typically include rotating buckets or blades and stationary nozzles. Steam is passed through a number of turbine stages. Each stage includes a row of stationary nozzles and rotating blades mounted to a rotor wheel. Steam expands through the number of turbine stages to rotate rotor wheel creating work.

The buckets are typically mounted to the rotor wheel through a dovetail attachment. The rotor wheel may include an internal, circumferential dovetail. Each bucket or blade has a corresponding dovetail that cooperates with the internal, circumferential dovetail. Generally, each rotor wheel features a loading position or gate opening configured to receive each bucket. Each bucket is mounted to the rotor wheel and manipulated into place about the outer diametric surface. Once all buckets are mounted, a closure bucket is installed in the loading portion and secured to the rotor wheel to prevent bucket liberation.

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of an exemplary embodiment, a method of removing a bucket from a turbomachine rotor wheel includes exposing a base portion of the bucket, positioning a pulling device radially outward of the base portion, connecting the base portion of the bucket to the pulling device through a linking rod, exerting a radially outwardly directed force on the linking rod through the pulling device, and removing the base portion from the rotor wheel.

According to another aspect of an exemplary embodiment, a method of removing a bucket from a rotor wheel includes positioning a ram radially outward of the base portion, connecting the base portion of the bucket to a ram, exerting a radially outwardly directed force on the base portion, and removing the base portion from the rotor wheel.

These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF DRAWINGS

The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is schematic view of a turbomachine shown in the form of a steam turbine in accordance with the prior art

FIG. 2 is a perspective view of a rotor wheel of the turbomachine ofFIG. 1;

FIG. 3 is a perspective view of a closure bucket spaced from the rotor wheel ofFIG. 2;

FIG. 4 is a perspective view of the closure bucket ofFIG. 3 installed in the rotor wheel;

FIG. 5 is a perspective view of a bucket portion of the closure bucket removed, in accordance with an exemplary embodiment;

FIG. 6 is a perspective view of a threaded opening formed in a base portion of the closure bucket ofFIG. 5, in accordance with an exemplary embodiment;

FIG. 7 is a perspective view of a pulling device coupled to the base portion of the closure bucket ofFIG. 6, in accordance with an exemplary embodiment;

FIG. 8 is a perspective view of the base portion of the closure bucket being removed from the rotor wheel by the pulling device, in accordance with an aspect of an exemplary embodiment; and

FIG. 9 is a perspective view of the base portion of the closure bucket being removed in pieces, in accordance with another aspect of an exemplary embodiment.

The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.

DETAILED DESCRIPTION OF THE INVENTION

A turbomachine is illustrated generally at2 inFIG. 1.Turbomachine2 is shown in the form of asteam turbine4 having aturbine housing16 that encloses a number of turbine stages three of which are indicated at20,21 and22. Of course, it would be appreciated by one of ordinary skill in the art that the number of turbine stages could vary. Each turbine stage20-22 includes a corresponding plurality of stationary airfoil members or nozzles, such as indicated at24 in connection withstage22, arranged upstream from a plurality of rotating airfoil members or buckets, such as shown at26. Rotatingairfoil members26 are mounted to arotor wheel30 withinsteam turbine4.

With this arrangement, steam from a boiler or similar arrangement (not shown) is directed intosteam turbine4. The steam expands through stages20-22 creating work that is used to power anexternal component34.External component34 may take on a variety of forms including a generator or a pump or other mechanically driven systems. That is,steam turbine4 could also be used as a power source for a vehicle.

In accordance with the exemplary embodiment illustrated inFIG. 2,rotor wheel30 includes arotor wheel body40 having afirst face42 and an opposing,second face43 that are joined by an outerdiametric surface45. Abucket receiving slot60 is formed in outerdiametric surface45.Bucket receiving slot60 supports plurality of rotatingairfoil members26 about outerdiametric surface45.Bucket receiving slot60 includes a bucket mounting opening63 andinterior cavity66 formed inrotor wheel body40. Each of the plurality of rotatingairfoil members26 includes a base portion72 (FIG. 3) that supports anairfoil portion73 and a mounting member ordovetail74.Airfoil portion73 includes aring element75 that forms part of a circumferentially extendingrotor ring76.Dovetail74 is shaped to nest withinbucket receiving slot60. Each of the plurality of rotatingairfoil members26 is guided intobucket receiving slot60 and manipulated into position. Once all buckets are installed, aclosure bucket80 is installed intobucket receiving slot60 and held in place by mechanical fasteners orgrub screws82 and84, such as shown inFIG. 4

Over the course of time,steam turbine4 may be taken offline for maintenance and/or repair. Maintenance includes an inspection of the buckets. During operation a bucket(s) may become damaged. The damaged bucket(s) is removed and replaced. Removing the damaged bucket first requires removal of theclosure bucket80 which may, itself, be damaged. In accordance with an aspect of an exemplary embodiment, removal of a damagedclosure bucket80 includes removinggrub screws82 and84 andairfoil portion73, as shown inFIG. 5, to expose anupper surface90 ofbase portion72. After removingairfoil portion73, abore96 is formed inclosure bucket80, as shown inFIG. 6. Bore96 extends radially inwardly intobase portion72. A plurality ofthreads100 are formed inbase portion72 alongbore96.

After formingthreads100, apulling device110 is arranged radially outward ofclosure bucket80, as shown inFIG. 7.Pulling device110 includes abase112 supported byrotor ring76 and aram114.Pulling device110 may rely upon air pressure, hydraulic pressure, or electrical current to operateram114. Ram114 is connected tobase portion72 through a linkingrod120. Linkingrod120 includes a plurality of threads (not separately labeled) that engage withthreads100 inbase portion72. Ram114 is actuated to exert a radially outwardly directed force onbase portion72 through linkingrod120. The radially outwardly directed force may causebase portion72 to release fromrotor wheel30, as shown inFIG. 8. At this point, the remaining buckets may be circumferentially shifted to bucket mounting opening63 and removed fromrotor wheel30 for inspection and/or replacement.

At this point it should be understood that the exemplary embodiments describe a method for removing a closure bucket from a rotor wheel. In the event that the closure bucket may does not release from rotor wheel, base portion and pin may be broken up into a plurality of pieces, indicated generally at140, and removed, as shown inFIG. 9. At this point, the remaining buckets may be circumferentially shifted tobucket mounting opening63 and removed. If the additional buckets resist removal efforts, all airfoil portions may be removed and corresponding base portions broken up intopieces140 to enable removal. It should also be understood that while described in terms of removing a bucket from a rotor wheel in a steam turbine, the method may also be employed to remove buckets from rotor wheels arranged in other turbomachine systems including compressors and gas turbines. Further, it should be understood that the method may be used to remove the closure bucket without requiring that the rotor wheel be separated from other rotor wheels or removed from the turbine rotor. The destruction of a single bucket, in situ, reduces downtime and overall maintenance costs associated with thesteam turbine4.

While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.

Claims (18)

What is claimed is:

1. A method of removing a bucket from a turbomachine rotor wheel, the method comprising:

exposing a base portion of the bucket, wherein exposing the base portion of the bucket includes removing an airfoil portion from the base portion;

positioning a puffing device radially outwardly of the base portion;

connecting the base portion of the bucket to the pulling device through a linking rod;

exerting a force on the linking rod, the force being exerted through the pulling device, the force being directed radially outwardly of the rotor wheel, the force forcing the linking rod radially outwardly from the rotor wheel into the pulling device; and

removing the base portion from the turbomachine rotor wheel.

2. The method ofclaim 1, wherein connecting the base portion of the bucket includes forming a bore into the base portion.

3. The method ofclaim 2, further comprising: forming a plurality of threads along the bore.

4. The method ofclaim 1, wherein positioning the pulling device includes supporting the pulling device on a rotor ring surrounding the turbomachine rotor wheel.

5. The method ofclaim 1, wherein positioning the pulling device includes supporting a ram radially outwardly of the base portion.

6. The method ofclaim 1, wherein exerting the radially outwardly directed force includes directing a hydraulic fluid into the pulling device.

7. The method ofclaim 1, wherein exerting the radially outwardly directed force includes operating a screw in the pulling device.

8. The method ofclaim 1, wherein removing the base portion further comprises:

breaking the base portion into multiple pieces; and

removing each of the multiple pieces from the turbomachine rotor wheel.

9. A method of removing a bucket from a rotor wheel comprising:

exposing a base portion of the bucket, the exposing including removing an airfoil portion from the base portion;

positioning a ram radially outwardly of the bucket;

connecting a base portion of the bucket to the ram;

exerting a radially outwardly directed force on the base portion, the exerting the radially outwardly directed force on the base portion includes forcing a linking rod radially outwardly from the rotor wheel into the ram; and

removing the base portion from the rotor wheel.

10. The method ofclaim 9, wherein connecting the base portion of the bucket includes forming a bore into the base portion.

11. The method ofclaim 10, further comprising: forming a plurality of threads along the bore.

12. The method ofclaim 11, wherein connecting the base portion to the ram includes establishing a threaded connection between the ram and the plurality of threads.

13. The method ofclaim 9, wherein positioning the ram includes supporting the ram on a rotor ring surrounding the rotor wheel.

14. The method ofclaim 9, wherein forcing the linking rod radially outwardly includes directing pressurized fluid into the ram.

15. The method ofclaim 14, wherein directing a pressurized fluid into the ram include urging hydraulic fluid into the ram.

16. The method ofclaim 9, wherein exerting the radially outwardly directed force includes directing an electrical current to the ram.

17. The method ofclaim 16, wherein the electrical current powers a screw.

18. The method ofclaim 9, wherein removing the base portion further comprises:

breaking the base portion into multiple pieces; and

removing each of the multiple pieces from the rotor wheel.

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